Expansion valve

ABSTRACT

An improved expansion valve is provided, which has a simple configuration and with which noise can be reduced. An expansion valve includes a valve main body having a valve chamber and a valve seat, a valve body configured to prevent passage of a fluid by being seated on the valve seat and allow passage of the fluid by separating from the valve seat, a coil spring configured to urge the valve body toward the valve seat, and an actuation rod configured to press the valve body toward a direction separating from the valve seat against an urging force applied from the coil spring, wherein the valve chamber includes a cylindrical inner wall being connected to the valve seat, the valve body includes a contact portion configured to be seated on the valve seat and a body portion having a tubular shape facing the inner wall, and the body portion includes connecting surfaces that are slidably in contact with the inner wall and plane surfaces that have a gap provided between the inner wall.

TECHNICAL FIELD

The present invention relates to an expansion valve.

BACKGROUND ART

Hitherto, in a refrigeration cycle system adopted in an air conditioner mounted on an automobile, for example, a temperature-sensitive expansion valve that adjusts an amount of a refrigerant passing therethrough according to temperature, with the aim to cut down installation space and piping.

In a general expansion valve, a spherical valve body arranged in a valve chamber is positioned to face a valve seat formed as an opening on the valve chamber. The valve body is supported by a valve body support arranged in the valve chamber and urged toward the valve seat by a coil spring arranged between a spring holding member attached to the valve main body and the valve body support. Then, the valve body is pressed by an actuation rod driven by a power element and moves away from the valve seat to allow passage of a refrigerant. The refrigerant that has passed through a throttle flow channel between the valve seat and the valve body is sent through an outlet port toward an evaporator.

At an initial timing when the refrigeration cycle system is started, a liquid density of the refrigerant passing through the throttle flow channel between the valve seat and the valve body is low, and a flow speed of the refrigerant increases as the flow resistance reduces. Therefore, a large friction noise tends to occur at a valve portion at the start of the refrigeration cycle system, and therefore, limiting of flow rate of the refrigerant is required as a countermeasure. Meanwhile, during a stable period in which a certain time has elapsed from the activation of the refrigeration cycle, friction noise becomes small since the liquid density becomes higher compared to when the refrigeration cycle is started. The flow rate during the stable period should not be limited excessively, and rather, there is a contradictory request of a need to ensure a sufficient refrigerant flow rate.

Patent Literature 1 discloses an expansion valve that defines a refrigerant inlet of the valve chamber and a gap between the valve body support and the valve chamber so as to realize a good balance between reduction of friction noise of the refrigerant when starting the refrigeration cycle system and ensuring a necessary flow rate of the refrigerant passing through the throttle flow channel.

CITATION LIST Patent Literature

-   [PTL 1] Publication of Japanese Patent No. 5369259

SUMMARY OF INVENTION Technical Problem

Meanwhile, noise caused by the refrigerant other than the friction noise is also generated in the expansion valve. For example, according to the expansion valve disclosed in Patent Literature 1, bubbles in the refrigerant may reach the valve seat without being collapsed and may burst simultaneously when the refrigerant passes through the valve seat, which may be recognized as noise.

Therefore, the present invention aims at providing an improved expansion valve having a simple configuration and with which noise can be reduced.

Solution to Problem

In order to achieve the above object, the expansion valve according to the present invention includes:

a valve main body including a valve chamber and a valve seat;

a valve body configured to prevent passage of a fluid by being seated on the valve seat and allow passage of the fluid by separating from the valve seat;

a coil spring configured to urge the valve body toward the valve seat; and

an actuation rod configured to press the valve body toward a direction separating from the valve seat against an urging force applied from the coil spring,

wherein the valve chamber includes a cylindrical inner wall being connected to the valve seat,

the valve body includes a contact portion configured to be seated on the valve seat and a body portion having a tubular shape facing the inner wall, and

in a cross section taken in a direction orthogonal to an axis of the valve body, a shape of an inner circumference of the inner wall differs from a shape of an outer circumference of the body portion, so that a space through which the fluid passes is formed between the inner wall and the body portion, and the inner circumference of the inner wall and the outer circumference of the body portion are partially slidably in contact with each other.

Advantageous Effects of Invention

The present invention provides an improved expansion valve having a simple configuration and with which noise can be reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating an example where an expansion valve according to a first embodiment is applied to a refrigerant cycle system.

FIG. 2 is a top view of a cross section taken at line A-A of FIG. 1.

FIG. 3 is a perspective view of a valve body according to the present embodiment.

FIG. 4 is a cross-sectional view illustrating a vicinity of a valve body of an expansion valve according to a second embodiment in enlarged view.

FIG. 5 is a top view of a cross section taken at line B-B of FIG. 4.

FIG. 6 is a perspective view of the valve body according to the present embodiment.

FIG. 7 is a cross-sectional view illustrating a vicinity of a valve body of an expansion valve according to a third embodiment in enlarged view.

FIG. 8 is a top view of a cross section taken at line C-C of FIG. 7.

FIG. 9 is a perspective view of the valve body according to the present embodiment.

FIG. 10 is a cross-sectional view of a body portion according to a modified example.

DESCRIPTION OF EMBODIMENTS Definition

In the present specification, a direction from a valve body 3 toward an actuation rod 5 is defined as an “upper direction”, and a direction from the actuation rod 5 toward the valve body 3 is defined as a “lower direction”. Therefore, according to the present specification, the direction from the valve body 3 toward the actuation rod 5 is referred to as the “upper direction” regardless of the orientation of an expansion valve 10.

In the present specification, a “polygonal tubular shape” refers to a tubular shape having a outer circumference that surrounds an axis with four or more plane surfaces. However, if there are connecting surfaces that connect the plane surfaces, such connecting surfaces are not included in the plane surfaces. Further, “the shape of the inner circumference being different from the shape of the outer circumference in cross section” means that the shape of the inner circumference is neither the same as nor similar to the shape of the outer circumference.

First Embodiment

A general configuration of the expansion valve 10 according to a first embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view illustrating an example where the expansion valve 10 according to the present embodiment is applied to a refrigerant cycle system 100. In the present embodiment, the expansion valve 10 is connected to a compressor 101, a capacitor 102 and an evaporator 104 that constitute the refrigerant cycle system 100.

The expansion valve 10 includes a valve main body 2 equipped with a cylindrical valve chamber VS, the valve body 3, an urging device 4, the actuation rod 5, and a ring spring 6.

The valve main body 2 includes a first flow channel 21 and a second flow channel 22 in addition to a valve chamber VS. The first flow channel 21 is a supply-side flow channel, for example, and a refrigerant, also referred to as a fluid, is supplied to the valve chamber VS via a supply-side flow channel. The second flow channel 22 is a discharge-side flow channel, for example, and the fluid in the valve chamber VS is discharged via an orifice portion 27 and the second flow channel 22 to the exterior of the expansion valve. The first flow channel 21 and the valve chamber VS are connected via a connection path 21 a having a smaller diameter than the first flow channel 21.

The valve chamber VS includes a valve seat 20 which is an inner circumference of a lower edge of the orifice portion 27 having a cylindrical shape, and a cylindrical inner wall 24 connected to the valve seat 20 and having a greater diameter than the valve seat 20.

FIG. 2 is a top view of a cross section taken at line A-A of FIG. 1, and it illustrates a cross section of the valve body 3 in a direction orthogonal to the axis. FIG. 3 is a perspective view of the valve body 3. In FIG. 3, the valve body 3 is formed by consecutively connecting a conical contact portion 31, a body portion 32 having a hexagonal tubular shape, a flange portion 33 having a disk shape, and an end portion 34 having a cylindrical shape.

A tapered surface 31 b of the contact portion 31 is abutted against the valve seat 20. An upper surface 31 a of the contact portion 31 is a plane surface that is orthogonal to an axis L. An outer circumference of the body portion 32 is composed of six plane surfaces 32 a and connecting surfaces 32 b that are formed between adjacent plane surfaces 32 a. Each connecting surface 32 b can either be a plane surface or a curved surface, and the peripheral length is preferably ¼ or less of the peripheral length of the plane surface 32 a. Further, the axial-direction length of the body portion 32 is preferably the same size as an inner diameter of an inner wall 24 of the valve chamber VS (or a maximum diagonal length of the body portion 32) or greater.

The valve body 3 is arranged in the valve chamber VS. In the cross section of FIG. 2, a shape of an inner circumference of the inner wall 24 of the valve chamber VS and a shape of an outer circumference of the body portion 32 differ, and according to an eccentricity of the valve chamber VS and the valve body 3, one of the connecting surfaces 32 b abut and slide against the inner wall 24 of the valve chamber VS. Meanwhile, regardless of the eccentricity of the valve chamber VS and the valve body 3, the inner wall 24 of the valve chamber VS does not abut against the plane surfaces 32 a. Therefore, the refrigerant will pass through the space formed between the inner wall 24 and the plane surfaces 32 a.

In FIG. 1, in a state where the valve body 3 is seated on the valve seat 20 having an annular shape arranged in the valve main body 2, the first flow channel 21 and the second flow channel 22 are in a non-communicated state. Meanwhile, in a state where the valve body 3 is separated from the valve seat 20, the first flow channel 21 and the second flow channel 22 are in a communicated state. However, there may be a case where a limited amount of refrigerant is allowed to pass through even when the valve body 3 is seated on the valve seat 20.

A lower end of the actuation rod 5 inserted to an actuation rod inserting hole 28 of the valve main body 2 and also inserted to the orifice portion 27 with a gap therebetween is in contact with the upper surface 31 a of the valve body 3 in a manner relatively displaceable in a direction intersecting the axis L. Further, the actuation rod 5 can press the valve body 3 toward a valve opening direction against an urging force applied from the urging device 4. In a state where the actuation rod 5 moves in the lower direction, the valve body 3 separates from the valve seat 20 and the expansion valve 10 will be in an opened state.

Next, a power element 8 for driving the actuation rod 5 will be described. In FIG. 1, the power element 8 is attached to a recessed portion 2 a provided on a top portion of the valve main body 2. The recessed portion 2 a is communicated via a communication path 2 b with a return flow channel 23 within the valve main body 2 through which the refrigerant from the evaporator 104 passes. The actuation rod 5 is passed through the communication path 2 b. A female screw is formed on an inner circumference of the recessed portion 2 a.

The power element 8 includes a plug 81, an upper lid member 82, a diaphragm 83, a stopper member 84, and a receiver member 86.

The upper lid member 82 includes a conical portion 82 a arranged at a center and a flange portion 82 b having an annular shape and extending from a lower end of the conical portion 82 a toward the outer circumference. An opening 82 c is formed at a top portion of the conical portion 82 a, which can be sealed by the plug 81.

The diaphragm 83 is formed of a thin plate material on which a plurality of corrugated shapes of concentric circles are formed, and it has an outer diameter that is approximately the same as an outer diameter of the flange portion 82 b.

The stopper member 84 includes a fitting hole 84 a formed at a center of a lower end thereof.

The receiver member 86 includes a flange portion 86 a having an outer diameter that is approximately the same as the outer diameter of the flange portion 82 b of the upper lid member 82, a stepped portion 86 c having an annular support surface 86 b that is substantially orthogonal to the axis L, and a hollow cylindrical portion 86 b. A male screw is formed on an outer circumference of the hollow cylindrical portion 86 b.

A process for assembling the power element 8 will be described. The upper lid member 82, the diaphragm 83, the stopper member 84 and the receiver member 86 are arranged so that they are in a positional relationship as illustrated in FIG. 1.

Further, in a state where the outer circumference portions of the flange portion 82 b of the upper lid member 82, the diaphragm 83 and the flange portion 86 a of the receiver member 86 are superposed, the outer circumference portions are subjected to girth welding by TIG welding, laser welding or plasma welding, for example, and integrated.

Next, after filling a space (pressure operation chamber PO) surrounded by the upper lid member 82 and the diaphragm 83 with operative gas through the opening 82 c formed on the upper lid member 82, the opening 82 c is sealed by the plug 81, and thereafter, the plug 81 is fixed to the upper lid member 82 by projection welding, for example.

In this state, the diaphragm 83 receives pressure from the operative gas filled in the pressure operation chamber PO in a direction pressing the diaphragm 83 toward the receiver member 86, so that the diaphragm 83 abuts against and is supported by an upper surface of the stopper member 84 arranged in a space (pressure detection chamber PD) surrounded by the diaphragm 83 and the receiver member 86.

During assembly of the power element 8, in a state where an upper end of the actuation rod 5 is fit to the fitting hole 84 a of the stopper member 84, the male screw on the hollow cylindrical portion 86 b of the receiver member 86 is screwed to the female screw on the recessed portion 2 a of the valve main body 2 that is communicated with the return flow channel 23, and the power element 8 is thereby fixed to the valve main body 2.

In this state, a packing PK is interposed between the power element 8 and the valve main body 2 so as to prevent leakage of the refrigerant from the recessed portion 2 a when the power element 8 is attached to the valve main body 2. In this state, the pressure detection chamber PD of the power element 8 is communicated with the return flow channel 23.

The ring spring 6 is a vibration absorption member that suppresses the vibration of the actuation rod 5. The ring spring 6 is arranged in an annular portion 26 adjacent to the actuation rod inserting hole 28 of the valve main body 2 and applies a predetermined elastic force to an outer circumference surface of the actuation rod 5 by a claw portion protruded to an inner circumference direction.

The urging device 4 includes a coil spring 41 formed by winding a round wire helically, and a spring holding member 43. The spring holding member 43 has a function to seal the opening of the valve chamber VS of the valve main body 2 and also has a function to support a lower end of the coil spring 41. An O-ring 44 is arranged between the spring holding member 43 and the inner wall of the valve chamber VS to prevent leakage of the refrigerant.

The valve body 3 illustrated in FIG. 3 is retained by having an upper end of the coil spring 41 abut against a lower side of the flange portion 33 and also having the end portion 34 fit to an inner side of the upper end of the coil spring 41

(Operation of Expansion Valve)

An operation example of the expansion valve 10 will be described with reference to FIG. 1. The refrigerant pressurized by the compressor 101 is liquefied in the capacitor 102 and sent to the expansion valve 10. Further, the refrigerant subjected to adiabatic expansion in the expansion valve 10 is sent to the evaporator 104, and in the evaporator 104, the refrigerant is subjected to heat exchange with the air flowing in a circumference of the evaporator. The refrigerant returning from the evaporator 104 is returned through the expansion valve 10 (more specifically, the return flow channel 23) toward the compressor 101.

A high-pressure refrigerant is supplied to the expansion valve 10 from the capacitor 102. More specifically, the high-pressure refrigerant from the capacitor 102 is supplied via the first flow channel 21 to the valve chamber VS.

In a state where the contact portion 31 of the valve body 3 is seated on the valve seat 20 (in other words, when the expansion valve 10 is in the closed state), the first flow channel 21 upstream of the valve chamber VS and the second flow channel 22 downstream of the valve chamber VS are in a non-communicated state. Meanwhile, in a state where the contact portion 31 of the valve body 3 is separated from the valve seat 20 (in other words, when the expansion valve 10 is in the opened state), the refrigerant supplied to the valve chamber VS is sent through the orifice portion 27 and the second flow channel 22 toward the evaporator 104.

According to the present embodiment, in a state where the contact portion 31 of the valve body 3 is separated from the valve seat 20, the refrigerant containing bubbles in the valve chamber VS is guided along the axial length of the body portion 32 through a relatively narrow gap between the plane surfaces 32 a of the body portion 32 of the valve body 3 and the inner wall 24, during which time the bubbles are gradually collapsed. Therefore, the bubbles will not collapse simultaneously when the refrigerant passes through the valve seat 20, so that the energy generated by the bursting of the bubbles is reduced and the noise generated during passage of the refrigerant is cut down. Further, by having the refrigerant flow along the plane surfaces 32 a along the axial length of the body portion 32, a flow straightening effect of the refrigerant is achieved.

Switching of the closed state and the opened state of the expansion valve 10 is carried out by the actuation rod 5 connected to the power element 8. In this state, the connecting surfaces 32 b of the body portion 32 sliding against the inner wall 24 has a long length corresponding to the axial length of the body portion 32, so that tilting that may be caused when the contact portion 31 of the valve body 3 separates from the valve seat 20 can be suppressed. Thus, further to the upper surface 31 a being relatively displaceable with respect to the actuation rod 5, smooth movement of the valve body 3 can be ensured.

In FIG. 1, the pressure operation chamber PO and the pressure detection chamber PD that are separated by the diaphragm 83 are provided inside the power element 8. Therefore, when the operative gas within the pressure operation chamber PO is liquefied, the actuation rod 5 moves to the upper direction, and when the liquefied operative gas is gasified, the actuation rod 5 moves to the lower direction. Thus, the switching between the valve-opened state and the valve-closed state of the expansion valve 10 is carried out.

Further, the pressure detection chamber PD of the power element 8 is communicated with the return flow channel 23. Therefore, the pressure of the refrigerant flowing through the return flow channel 23 is transmitted via the stopper member 84 and the diaphragm 83 to the operative gas inside the pressure operation chamber PO. Thereby, the volume of the operative gas inside the pressure operation chamber PO is changed, and the actuation rod 5 is driven. In other words, according to the expansion valve 10 illustrated in FIG. 1, the amount of the refrigerant supplied from the expansion valve 10 to the evaporator 104 is automatically adjusted according to the pressure of the refrigerant returning from the evaporator 104 to the expansion valve 10.

Second Embodiment

Next, an expansion valve according to a second embodiment will be described. FIG. 4 is a cross-sectional view illustrating a vicinity of a valve body of an expansion valve 10A in enlarged view. FIG. 5 is a top view of a cross section taken at line B-B of FIG. 4. FIG. 6 is a perspective view of the valve body 3A.

In FIG. 6, the valve body 3A is formed by consecutively connecting a conical contact portion 31A, a body portion 32A having a hexagonal tubular shape, and an end portion 34A having a cylindrical shape.

A tapered surface 31Ab of the contact portion 31A is abutted against the valve seat 20. Further, an upper surface 31Aa of the contact portion 31A is a plane surface that is orthogonal to the axis L. An outer circumference of the body portion 32A is composed of six plane surfaces 32Aa and connecting surfaces 32Ab that are formed between adjacent plane surfaces 32 a. Each connecting surface 32 b can either be a plane surface or a curved surface. The peripheral length of the body portion 32A is preferably the same size as a diameter of an inner wall 24A of the valve chamber VS (or a maximum diagonal length of the body portion 32) or greater. The connecting surfaces 32Ab constitute a sliding contact portion, and the plane surfaces 32Aa constitute a flow channel portion.

An inner wall 24A of the valve chamber VS is formed greater than an outer diameter of the coil spring 41. The other configurations are similar to the above-described embodiment, so the similar components are denoted with the same reference numbers and detailed descriptions thereof are omitted.

According to the present embodiment, in a state where the contact portion 31A of the valve body 3A is separated from the valve seat 20, the refrigerant containing bubbles in the valve chamber VS is guided along the axial length of the body portion 32A through a relatively narrow gap between the plane surfaces 32Aa of the body portion 32A of the valve body 3A and the inner wall 24A, during which time the bubbles are gradually collapsed. Therefore, the bubbles will not collapse simultaneously when the refrigerant passes through the valve seat 20, so that the energy generated by the bursting of the bubbles is reduced and the noise generated during passage of the refrigerant is cut down. Further, by having the refrigerant flow along the plane surfaces 32Aa along the axial length of the body portion 32A, a flow straightening effect of the refrigerant is achieved.

Since the connecting surfaces 32Ab of the body portion 32A that abut against the inner wall 24A during opening and closing of the valve have a long length corresponding to the axial length of the body portion 32A, tilting caused when the contact portion 31A of the valve body 3A separates from the valve seat 20 can be suppressed. Thus, further to the upper surface 31Aa being relatively displaceable with respect to the actuation rod 5, smooth movement of the valve body 3 can be ensured.

Especially since the position in which the connecting surfaces 32Ab abut against the inner wall 24A is relatively distant from the axis L, tilting of the valve body 3A can be suppressed effectively.

Third Embodiment

Next, an expansion valve according to a third embodiment will be described. FIG. 7 is a cross-sectional view illustrating a vicinity of a valve body of an expansion valve 10B in enlarged view. FIG. 8 is a top view of the cross section taken at line C-C of FIG. 7. FIG. 9 is a perspective view of a valve body 3B.

In FIG. 9, the valve body 3B is formed by consecutively connecting a conical contact portion 31B, a body portion 32B having a cylindrical shape, a flange portion 33B having a disk shape, and an end portion 34B having a cylindrical shape.

A tapered surface 31Bb of the contact portion 31B is abutted against the valve seat 20. Further, an upper surface 31Ba of the contact portion 31B is a plane surface that is orthogonal to the axis L. The length of the body portion 32B should preferably be the same as a maximum diagonal length of an inner wall 24B of the valve chamber VS (or a diameter of the body portion 32B) or greater.

As illustrated in FIG. 8, the inner wall 24B of the valve chamber VS has a hexagonal tubular shape formed of six plane surfaces 24Bb. The outer circumference of the body portion 32B of the valve body 3B is in contact with the plane surfaces 24Bb at any of the six contact points CP illustrated in FIG. 8. Therefore, the contact point CP at the outer circumference surface of the body portion 32B constitutes a sliding contact portion, and the outer circumference surface between adjacent contact points CP constitutes a flow channel portion. The other configurations are similar to the embodiment described above, so they are denoted with the same reference numbers and detailed descriptions thereof are omitted.

According to the present embodiment, in a state where the contact portion 31B of the valve body 3B is separated from the valve seat 20, the refrigerant containing bubbles in the valve chamber VS is guided along the axial length of the body portion 32B through a relatively narrow gap between the outer circumference surface of the body portion 32B of the valve body 3B and the inner wall 24B, during which time the bubbles are gradually collapsed. Therefore, the bubbles will not collapse simultaneously when the refrigerant passes through the valve seat 20, so that the energy generated by the bursting of the bubbles is reduced and the noise generated during passage of the refrigerant is cut down. Further, by having the refrigerant flow along the plane surfaces 24Bb along the axial length of the body portion 32B, a flow straightening effect of the refrigerant is achieved.

Since the plane surfaces 24Bb that abut against the body portion 32B have a long length corresponding to the axial direction of the valve body 3B, tilting caused when the contact portion 31B of the valve body 3B separates from the valve seat 20 can be suppressed. Thus, further to the upper surface 31Ba being relatively displaceable with respect to the actuation rod 5, smooth movement of the valve body 3B can be ensured.

Modified Example

FIG. 10 is a view similar to FIG. 2 illustrating a cross section of a valve body and an inner wall of a valve chamber according to a modified example. In the present modified example, an inner wall 24D of a valve chamber at a valve main body 2D is a cylindrical surface, whereas a body portion 32D of the valve body has a non-round cross section. Specifically, the body portion 32D is formed of a partially cylindrical surface 32Da and a plane surface 32Db. The width of the plane surface 32Db is shorter than a diameter of the partially cylindrical surface 32Da. A cross-sectional shape of the body portion 32D is the same throughout the whole length of the body portion 32D. The partially cylindrical surface 32Da constitutes the sliding contact portion, and the plane surface 32Db constitutes the flow channel portion. The other configurations are similar to the embodiments described earlier, so they are denoted with the same reference numbers, and detailed descriptions thereof are omitted.

According to the present modified example, in a state where the valve body is separated from the valve seat, the refrigerant containing bubbles in the valve chamber is guided along the axial length of the body portion 32D through a relatively narrow gap between the plane surface 32Db of the body portion 32D of the valve body and the inner wall 24D, during which time the bubbles are gradually collapsed. Therefore, the bubbles will not collapse simultaneously when the refrigerant passes through the valve seat, so that the energy generated by the bursting of the bubbles is reduced and the noise generated during passage of the refrigerant is cut down. Further, by having the refrigerant flow along the plane surface 32Db along the axial length of the body portion 32D, a flow straightening effect of the refrigerant is achieved.

The present invention is not limited to the above-described embodiments. Arbitrary components of the above-described embodiments can be modified within the scope of the present invention. Further, arbitrary components can be added to or omitted from the above-described embodiments. For example, the flow channel portion is not limited to being a plane surface, and it can be a protruded curved surface or a recessed curved surface.

REFERENCE SIGNS LIST

-   10, 10A, 10B: expansion valve -   2, 2A, 2B 2D: valve main body -   3, 3A, 3B: valve body -   4: urging device -   5: actuation rod -   6: ring spring -   8: power element -   20: valve seat -   21: first flow channel -   22: second flow channel -   23: return flow channel -   26: annular portion -   27: orifice portion -   41: coil spring -   42: valve body support -   43: spring holding member -   100: refrigerant cycle system -   101: compressor -   102: capacitor -   104: evaporator -   VS: valve chamber 

1. An expansion valve comprising: a valve main body comprising a valve chamber and a valve seat; a valve body configured to limit passage of a fluid by being seated on the valve seat and allow passage of the fluid by separating from the valve seat; a coil spring configured to urge the valve body toward the valve seat; and an actuation rod configured to press the valve body toward a direction separating from the valve seat against an urging force applied from the coil spring, wherein the valve chamber comprises a cylindrical inner wall being connected to the valve seat, the valve body comprises a contact portion configured to be seated on the valve seat and a body portion having a tubular shape facing the inner wall, in a cross section taken in a direction orthogonal to an axis of the valve body, a shape of an inner circumference of the inner wall differs from a shape of an outer circumference of the body portion, so that a space through which the fluid passes is formed between the inner wall and the body portion, and the inner circumference of the inner wall and the outer circumference of the body portion are partially slidably in contact with each other, bubbles in the fluid are collapsed when the fluid passes through the space formed between the inner wall and the body portion, and the fluid passes the valve seat after passing through the space formed between the inner wall and the body portion.
 2. The expansion valve according to claim 1, wherein the inner wall comprises a cylindrical shape, and the body portion comprises a polygonal tubular shape.
 3. The expansion valve according to claim 1, wherein the inner wall comprises a polygonal tubular shape, and the body portion comprises a cylindrical shape.
 4. The expansion valve according to claim 1, wherein the inner wall comprises a cylindrical shape, and the body portion comprises a non-round cross section.
 5. The expansion valve according claim 1, wherein the actuation rod and the valve body are abutted against each other in a relative displaceable manner. 